The present invention relates to an image forming system that is structured by connecting a post-processing apparatus to an image forming apparatus.
A post-processing apparatus having functions to conduct various types of post-processing is connected to a high speed image forming apparatus as in the case of an electrophotographic image forming apparatus.
In post-processing apparatuses, there is one, for example, wherein plural post-processing functions are provided in one apparatus such as a post-processing apparatus equipped with a punching function and a folding function. However, for the purpose of allowing various post-processing to be possible, it becomes difficult to make one apparatus to have many types of post-processing functions, and plural post-processing apparatuses are connected to an image forming apparatus to construct an image forming system, to realize a multifunctional image forming system.
For example, in Japanese Patent Publication Open to Public Inspection No. 2005-206264 an image forming system is disclosed, wherein three post-processing apparatuses are connected to an image forming apparatus, and book binding processing and stitching-processing including punching processing, various types of folding processing and cutting, are conducted for the sheet on which an image has been formed.
In the structure of a conventional image forming system, it is unavoidable that a sheet conveyance path of the post-processing apparatus becomes long because plural post-processing apparatuses are connected to an image forming apparatus in series, and this long conveyance path causes various points to be improved.
Main points are as follows. (1) Electric power is consumed wastefully, which is not preferable from the viewpoint of energy saving, and running cost is increased. For example, even in the case of a print job requiring no post-processing, all conveyance devices of the system are driven to eject the sheet to a sheet ejection section of the post-processing device on the rearmost part. (2) Since the conveyance path becomes long, the probability of an occurrence of conveyance troubles is enhanced, and stability and reliability of the conveyance system are declined. (3) When conveyance troubles such as jamming are caused, the system is stopped, and this stop increases the number of sheets remaining in the conveyance path, resulting in an increase of waste of sheets, and workability of jam recovery such as removal of sheets is lowered. (4) A trouble of a single apparatus makes the total system to break down, which causes the system to be fragile. (5) Because of a restriction for sheet conveyance, the number of post-processing apparatuses is limited, which limits the realization of the multifunctional image forming system.
The image forming system formed by connecting plural post-processing apparatuses to an image forming apparatus has many points to be improved as stated above, and it is considered to connect various combinations of an image forming apparatus and a post-processing apparatus to a network. In this case, an image forming apparatus is connected to each post-processing apparatus, thus, image forming apparatuses of the same number as that of post-processing apparatuses are required, resulting in problems in terms of installation space and installation cost, which makes it difficult to put the image forming system to practical use.
Further, it is extremely difficult to maintain evenly output functions between each unit of the image forming apparatuses, and the image forming system formed through network connection is insufficient for needs for high level image quality such as a field of POD (POINT ON DEMAND).